Sheryl Sandberg, chief operating officer of Facebook Inc.

Sheryl Sandberg, chief operating officer of Facebook Inc., center, speaks during a television interview on day two of the World Economic Forum (WEF) in Davos, Switzerland, on Thursday, Jan. 24, 2013.

Sheryl Sandberg, chief operating officer of Facebook Inc., center, speaks during a television interview on day two of the World Economic Forum (WEF) in Davos, Switzerland, on Thursday, Jan. 24, 2013. (Simon Dawson, Bloomberg)

Sheryl Sandberg, chief operating officer of Facebook Inc., center, speaks during a television interview on day two of the World Economic Forum (WEF) in Davos, Switzerland, on Thursday, Jan. 24, 2013.